This invention relates to an improvement of a magnetic recording medium, and particularly to a magnetic recording medium with an improved durability against a magnetic head.
Research and development of continuous magnetic films for use as a continuous magnetic recording medium have been made for a higher density magnetic recording.
Magnetic recording media are prepared by forming a thin film of an alloy or a compound containing a ferromagnetic metal such as Fe, Co, Ni, etc. on a substrate of non-magnetic material such as a polymer film, aluminum, glass, etc. by vacuum evaporation, sputtering, plating, etc. Magnetic recording media have such problems that the surface of a magnetic film will wear when used in direct contact with a magnetic head for recording and reproduction, the magnetic head will be damaged through contact with the magnetic film, and the magnetic film will be deteriorated by corrosion, etc. through contact with a humid atmosphere.
To solve these problems, it has been proposed to form a protective layer composed of a hard material such as SiO.sub.2, Al.sub.2 O.sub.3, Cr.sub.2 O.sub.3, SiC, TiC, etc. on the surface of a magnetic film [Japanese Patent Application Kokai (Laid-Open) Nos. 50-104602 and 58-130437], or to form a metal film of Au, Pt, Rh, Pd, Al, etc. as a protective layer on the surface of a magnetic film [Japanese Patent Application Kokai (Laid-open) Nos. 53-40505 and 57-176537]. However, the present inventors have found that the metallic protective film has no sufficient durability against the sliding with a magnetic head or no sufficient resistance against corrosion, whereas the protective film composed of the compound-based hard material has a low impact resistance and a high liability to damage the magnetic head.
The requirements for a protective film are a thorough chemical and mechanical protection of a magnetic film and a less liability to damage the magnetic head. The prior art protective film has paid no thorough considerations to these requirements, and still has such problems as an insufficient protective action on the magnetic film and a high liability to damage the magnetic head.